Deltiology (from Greek δελτίον, deltion, diminuitive of δέλτος, deltos, "tablet, letter"; and -λογία, -logia) is the study and collection of postcards. Compared to philately, the iden- tification of a postcard's place and time of production can often be an impossible task because postcards, unlike stamps, are produced in a decentralised, unregulated manner. For this reason, some collectors choose to limit their acquisitions to cards by specific artists and publishers, or by time and location.

The name Esztergom was first mentioned in 1079. Some think the name comes from Isztergam (Iszter meaning Danube and Gam referring to the nearby river Garam). The town is the seat of Etzel/Attila in the Niebelungenlied as Gran. In Croatian Ostrogon, in Polish Ostrzyhom, in Slovak Ostrihom, in Latin Strigonium, in Turkish Estergon.